The difference is between the breath as what is breathed (spirit) and the breathing itself (soul). They are similar to the difference between arabic Nafs and Ruh in this respect, but Spirit is seen as something higher than the soul while the Nafs is seen as something lower than the soul. It helps to translate across to another language whose roots actually mean something like Arabic for instance, but other translations to languages with roots is also good to explore cross-cultural differences in meanings.
It is of interest that in many traditional cultures there are always two different words related to the core of the self, and normally one of them stays with the body in death and the other goes away somewhere. So in Arabic for instance it is the Ruh that goes away to God (Ywhw/Allah) while it is the Nafs that is tied to the body. Thus in Sufism whose coda is “Die before you die” is all about purifying the Nafs into the Ruh, but they are considered to be basically the same thing. While in other traditional cultures many times there is a difference in kind between the to etherial parts of the self.
In Egyptian religion the two parts of the soul are called Ka and Ba. http://www.philae.nu/akhet/KaBa.html
Hillman always connected Spirit to monotheism and Soul to the Imaginal of Archetypal Psychology which is related to Images. I do not believe that this is particularly correct but it does seem to be a trend to denounce the Spirit and return to the Soul as central. Spirit is latin and Soul is Old English. Spirit really does mean Air, and Soul has to do with something like the waves of the Sea that suggests breathing. So I think that the relation of Spirit to Soul is closer to the use of Nafs and Ruh only we see the spirit as being tied to the transcendental in our culture and the breathing as tied to the body, while in Arab culture it was the other way around.
We talk about Spirituality rather than religion which many find more acceptable because it is not dogmatic, and seems to be expressed in mystical paths across religions. Soul on the other hand is something closer to ourselves as living creatures. We talk about music being soulful for instance.
Spirituality has opened up a nihilistic market place where everyone and their brother are selling the snake oil of enlightenment for a fist full of dollars. Zizek says that this idea of Spirituality is the ideology of our day, which is caught up in the denial of ideology. And he says that, along with Adorno, that it is precisely what the state wants that we give up thinking, and will. He also says this new “oriental” ideology of spirituality, is basically a support for corporatism which I rail about elsewhere. I think he has a point there, although I think this only applies to the superficial nihilistic versions of these “oriental” religious philosophies and there are more genuine versions of them which are nondual in character for which you cannot make the same argument. Buddhism for instance does have a moral stance in the world even if some of its versions like Zen seem to have given up that stance, as it was incorporated into culture and interpreted more widely. One of my favorite movies is called Satori which is about a monster that eats thoughts. This is an interesting popular interpretation of Zen buddhism that may have some truth. I believe that Hui Neng tried to straighten out this kink in Zen in the Platform Sutra and the Southern School of Chan.
I think to the extent that people think of Spirit as a transcendental and soul as immanent to the body they are mistaken about the nature of enlightenment. At least in original Buddhism emptiness is nondual and is neither transcendent nor immanent. Same is true of Taoism with regard to the void. Other deeper nondual paths like DzogChen that merges the idea of Emptiness and Void somehow are even less likely to be associated with even the duality between nonduals like emptiness/void. I like the idea of reappropriating Old English terms like Feorh as having this nondual meaning. Feorh is not Geist which is Ghost in Old English. Rather it is connected to the blood and via that to life, and means also spirit, but probably originally in the sense of spirited. I would place Feorh as the nondual barzak (interspace/barrier) between soul and spirit or ruh and nafs. The reversal that makes spirit into nafs and soul into ruh is very telling, because it is precisely the seeking of a transcendental that throws you back into a degenerate form of immanence. What is closer to us the Soul is that which can be purified into the Ruh. But both of these duals, nafs/ruh or spirit/soul are separated by something nondual. In English I want to say that is the Feorh the original spiritedness that lives in the blood and is not the Ghost/Geist which becomes Mind/Spirit in German as seen in Hegel’s Phenomenology of Spirit/Ghost/Mind.
In Sufism it is precisely the death of the Nafs that yields the Ruh in its purity. And so that dividing line between life and death is makes the distinction and that realm between life and death is called the Barzak which separates use from life in the next world through the time in the grave before bodily resurrection. Nafs in this sense which is I in Arabic means something like the ego. Ruh means something like what Soul means traditionally, as something preserved after death that exists in the grave and goes to the garden or fire after the resurrection with the body. Ruh means the purified self in a nondual state in my opinion. This is equivalent to the return to the orignal purity of children in some sense free of defilements that cling to the self. It is interesting that Jesus is referred to as the Ruh of Allah in Quran. Thus from an Islamic perspective what is special about Jesus is that he embodies, as we see him in the Injeel (Gospel of Thomas) as the wholly purified human being, the epitome of what we should associate with Spirituality. All other previous Prophets are in the position of Nafs to the Ruh of Allah, i.e. Jesus. The Barzak, i.e. nondual between these two kinds of Prophet is of course Muhammad. Within Muhammad (pbuh) are the nafs of all previous Prophets together with the Pure Ruh of Jesus which is the extreme of enlightenment without regard for immanence. What we see in Muhammad’s life is that this other option has its own characteristics and structure which we know about because Muhammad is a historical figure. We know more about Muhammad than any other human being alive or dead. So the Way of Muhammad is very clearly exemplified by all we know of him in his prophetic career. He single-handedly generated a heresy of the Western Worldview which was successful, unlike other Heresies that were crushed. Even when the Christians went to war against Islam they could not crush it. No one less than Nietzsche, unlikely as it may seem, has many good things to say about Islam. It is unfortunate in our time that some people calling themselves Muslims have decided to ruin that reputation, by doing horrific things in the name of this religion.
Anyway, when you see the difference between Ruh and Nafs as embodied in the prophets and you see Muhammad as the middle way between these two duals then that concrete embodiment in myth and history can give you a really good idea that these terms mean in Arabic and Islamic Sufism and that helps clarify in my opinion the relation between Soul/Feorh/Geist in Old English which I believe is something similar even though it is a completely different culture, and I would claim this is wide-spread. So for instance you have Ba/Akh/Ka in Egypt. Notice that the house of Allah in Mekkah is called the Kaba. I don’t think that is an accident.
We could go on to look at the Chinese idea of the split immaterial self called Hun and Po with Shen being the nondual barrier/interspace between them. http://en.wikipedia.org/wiki/Hun_and_po
The problem we have is that we have lost the roots of Old English because so many words like Feorh have been lost in the oblivion of language change as French, Latin, and Greek words rushed in via a former colonialization of the Angles and Saxons. But this gives us an opportunity to reclaim those words and use them for the lost sense of nonduality that was replaced by the radical duality of the Western Tradition. The key question here is what is the difference that makes a difference ala Bateson between Soul and Spirit. Spirit is the foreign word and Soul the indigenous word. But beneath that colonial overlay is the difference between Geist and Soul. Geist is only Ghost in English but in German it became the word for Mind and Spirit. Soul is the breathing, based on its connection to the sea, and Geist is the Spirit, i.e. what is breathed out as the last breath, what leaves the body on death, but then sometimes hangs around. Of course then the question is to think the Feorh as Spiritedness that is somehow in the Blood rather than in the Breath and Breathing. The heartbeat can be seen as more central to life than the Breath, we can hold our breaths for a minute or more but we cannot stop our hearts beating pumping blood throughout the bodymind. There are more heartbeats in our lives than breaths by a multiple of four I believe, if I remember rightly. All animals have about the same number of breaths and heartbeats in their lives regardless of their size and the difference is how fast they go, while humans have about 1/3 more than all other animals. So if Feorh is rooted in heartbeats and the blood flowing as the basis of “Spiritedness” leading to a kind of spirit then its complementarity between the moments of pumping is more central to us than the difference between our breathing and the air breathed. And of course when we enter the realm of the heart it is a whole different region of the psyche than that governed by the breath and its breathing. The Blood and its pumping is both part of the organism, while the breath is foreign to the organism and the breathing is the way we intervene with respect to this foreign substance, as invisible as it is, to take life from it via oxygen produced symbiotically by plants. Both pumping and what is pumped are intrinsic to the organism while breath is extrinsic while breath is intrinsic. And of course now we know the blood carries that oxygen to the cells so that the two are interlinked. This interlinking of Breath and Blood is were we start to see the nondual aspect of what can be seen as duals. Breath and Breathed is Self/InvisibleOther, while Pumped and Pumping is Self/Selfing instead. But the fact that Self/Selfing transportation is transporting with comes from the Self/InvisibleOther distinction and dynamic means that the two are symbiotically interrelated and cannot be separated which is what makes them nondual. Nondual means that they cannot be divided, yet not because they are One, and not because their difference is illusory but because the difference is a necessity that is self reinforcing since both are intrinsic to life and one actually carries the other and the exhaling puts out the carbon dioxide that is necessary for our symbiosis with the plants. Blood also carries food, but we do not need to go there to prove our point Blood plays simultaneous roles in making life possible.
Note “pbuh” stands for “Peace Be Upon Him” which is a term of respect applied by Muslims to Muhammad especially but also to other prophets.